Lamellae spatial distribution modulates fracture behavior and toughness of african pangolin scales

Michael J. Chon; Matthew Daly; Bin Wang; Xianghui Xiao; Alireza Zaheri; Marc A. Meyers; Horacio D. Espinosa

doi:10.1016/j.jmbbm.2017.06.009

Lamellae spatial distribution modulates fracture behavior and toughness of african pangolin scales

Michael J. Chon, Matthew Daly, Bin Wang, Xianghui Xiao, Alireza Zaheri, Marc A. Meyers, Horacio D. Espinosa^*

^*Corresponding author for this work

Mechanical Engineering

Research output: Contribution to journal › Article › peer-review

10 Scopus citations

Abstract

Pangolin scales form a durable armor whose hierarchical structure offers an avenue towards high performance bio-inspired materials design. In this study, the fracture resistance of African pangolin scales is examined using single edge crack three-point bend fracture testing in order to understand toughening mechanisms arising from the structures of natural mammalian armors. In these mechanical tests, the influence of material orientation and hydration level are examined. The fracture experiments reveal an exceptional fracture resistance due to crack deflection induced by the internal spatial orientation of lamellae. An order of magnitude increase in the measured fracture resistance due to scale hydration, reaching up to ~ 25 kJ/m² was measured. Post-mortem analysis of the fracture samples was performed using a combination of optical and electron microscopy, and X-ray computerized tomography. Interestingly, the crack profile morphologies are observed to follow paths outlined by the keratinous lamellae structure of the pangolin scale. Most notably, the inherent structure of pangolin scales offers a pathway for crack deflection and fracture toughening. The results of this study are expected to be useful as design principles for high performance biomimetic applications.

Original language	English (US)
Pages (from-to)	30-37
Number of pages	8
Journal	Journal of the Mechanical Behavior of Biomedical Materials
Volume	76
DOIs	https://doi.org/10.1016/j.jmbbm.2017.06.009
State	Published - Dec 2017

Keywords

Bio-inspired design principles
Biomaterials
Fracture toughness
Hierarchical structure
Pangolin scale

ASJC Scopus subject areas

Biomaterials
Biomedical Engineering
Mechanics of Materials

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10.1016/j.jmbbm.2017.06.009

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@article{70196da54f154127983d38ec48197180,

title = "Lamellae spatial distribution modulates fracture behavior and toughness of african pangolin scales",

abstract = "Pangolin scales form a durable armor whose hierarchical structure offers an avenue towards high performance bio-inspired materials design. In this study, the fracture resistance of African pangolin scales is examined using single edge crack three-point bend fracture testing in order to understand toughening mechanisms arising from the structures of natural mammalian armors. In these mechanical tests, the influence of material orientation and hydration level are examined. The fracture experiments reveal an exceptional fracture resistance due to crack deflection induced by the internal spatial orientation of lamellae. An order of magnitude increase in the measured fracture resistance due to scale hydration, reaching up to ~ 25 kJ/m2 was measured. Post-mortem analysis of the fracture samples was performed using a combination of optical and electron microscopy, and X-ray computerized tomography. Interestingly, the crack profile morphologies are observed to follow paths outlined by the keratinous lamellae structure of the pangolin scale. Most notably, the inherent structure of pangolin scales offers a pathway for crack deflection and fracture toughening. The results of this study are expected to be useful as design principles for high performance biomimetic applications.",

keywords = "Bio-inspired design principles, Biomaterials, Fracture toughness, Hierarchical structure, Pangolin scale",

author = "Chon, {Michael J.} and Matthew Daly and Bin Wang and Xianghui Xiao and Alireza Zaheri and Meyers, {Marc A.} and Espinosa, {Horacio D.}",

note = "Funding Information: The authors gratefully acknowledge financial support from a Multi-University Research Initiative through the Air Force Office of Scientific Research ( AFOSR-FA9550-15-1-0009 ). We would like to acknowledge Scott Tremor from the San Diego Natural History Museum for providing the pangolin scales. M.D. would like to acknowledge financial support under the Postdoctoral Fellowships Program (Application No.: PDF-502224-2017 ) from the Natural Sciences and Engineering Research Council (NSERC) of Canada. This work made use of the EPIC, Keck-II, and/or SPID facilities of Northwestern University's NUANCE Center. Appendix A Funding Information: The authors gratefully acknowledge financial support from a Multi-University Research Initiative through the Air Force Office of Scientific Research (AFOSR-FA9550-15-1-0009). We would like to acknowledge Scott Tremor from the San Diego Natural History Museum for providing the pangolin scales. M.D. would like to acknowledge financial support under the Postdoctoral Fellowships Program (Application No.: PDF-502224-2017) from the Natural Sciences and Engineering Research Council (NSERC) of Canada. This work made use of the EPIC, Keck-II, and/or SPID facilities of Northwestern University's NUANCE Center. Publisher Copyright: {\textcopyright} 2017 Elsevier Ltd",

year = "2017",

month = dec,

doi = "10.1016/j.jmbbm.2017.06.009",

language = "English (US)",

volume = "76",

pages = "30--37",

journal = "Journal of the Mechanical Behavior of Biomedical Materials",

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T1 - Lamellae spatial distribution modulates fracture behavior and toughness of african pangolin scales

AU - Chon, Michael J.

AU - Daly, Matthew

AU - Wang, Bin

AU - Xiao, Xianghui

AU - Zaheri, Alireza

AU - Meyers, Marc A.

AU - Espinosa, Horacio D.

N1 - Funding Information: The authors gratefully acknowledge financial support from a Multi-University Research Initiative through the Air Force Office of Scientific Research ( AFOSR-FA9550-15-1-0009 ). We would like to acknowledge Scott Tremor from the San Diego Natural History Museum for providing the pangolin scales. M.D. would like to acknowledge financial support under the Postdoctoral Fellowships Program (Application No.: PDF-502224-2017 ) from the Natural Sciences and Engineering Research Council (NSERC) of Canada. This work made use of the EPIC, Keck-II, and/or SPID facilities of Northwestern University's NUANCE Center. Appendix A Funding Information: The authors gratefully acknowledge financial support from a Multi-University Research Initiative through the Air Force Office of Scientific Research (AFOSR-FA9550-15-1-0009). We would like to acknowledge Scott Tremor from the San Diego Natural History Museum for providing the pangolin scales. M.D. would like to acknowledge financial support under the Postdoctoral Fellowships Program (Application No.: PDF-502224-2017) from the Natural Sciences and Engineering Research Council (NSERC) of Canada. This work made use of the EPIC, Keck-II, and/or SPID facilities of Northwestern University's NUANCE Center. Publisher Copyright: © 2017 Elsevier Ltd

PY - 2017/12

Y1 - 2017/12

N2 - Pangolin scales form a durable armor whose hierarchical structure offers an avenue towards high performance bio-inspired materials design. In this study, the fracture resistance of African pangolin scales is examined using single edge crack three-point bend fracture testing in order to understand toughening mechanisms arising from the structures of natural mammalian armors. In these mechanical tests, the influence of material orientation and hydration level are examined. The fracture experiments reveal an exceptional fracture resistance due to crack deflection induced by the internal spatial orientation of lamellae. An order of magnitude increase in the measured fracture resistance due to scale hydration, reaching up to ~ 25 kJ/m2 was measured. Post-mortem analysis of the fracture samples was performed using a combination of optical and electron microscopy, and X-ray computerized tomography. Interestingly, the crack profile morphologies are observed to follow paths outlined by the keratinous lamellae structure of the pangolin scale. Most notably, the inherent structure of pangolin scales offers a pathway for crack deflection and fracture toughening. The results of this study are expected to be useful as design principles for high performance biomimetic applications.

AB - Pangolin scales form a durable armor whose hierarchical structure offers an avenue towards high performance bio-inspired materials design. In this study, the fracture resistance of African pangolin scales is examined using single edge crack three-point bend fracture testing in order to understand toughening mechanisms arising from the structures of natural mammalian armors. In these mechanical tests, the influence of material orientation and hydration level are examined. The fracture experiments reveal an exceptional fracture resistance due to crack deflection induced by the internal spatial orientation of lamellae. An order of magnitude increase in the measured fracture resistance due to scale hydration, reaching up to ~ 25 kJ/m2 was measured. Post-mortem analysis of the fracture samples was performed using a combination of optical and electron microscopy, and X-ray computerized tomography. Interestingly, the crack profile morphologies are observed to follow paths outlined by the keratinous lamellae structure of the pangolin scale. Most notably, the inherent structure of pangolin scales offers a pathway for crack deflection and fracture toughening. The results of this study are expected to be useful as design principles for high performance biomimetic applications.

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KW - Fracture toughness

KW - Hierarchical structure

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JO - Journal of the Mechanical Behavior of Biomedical Materials

JF - Journal of the Mechanical Behavior of Biomedical Materials

ER -

Lamellae spatial distribution modulates fracture behavior and toughness of african pangolin scales

Abstract

Keywords

ASJC Scopus subject areas

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